Method and magnetic resonance apparatus for echo planar imaging with data entry into k-space along a zigzag trajectory

Abstract

In a method and apparatus for echo planar magnetic resonance (MR) imaging sequence of phase encoding gradient fields and a sequence of readout gradient fields are applied in order to produce a well-defined zigzag-type trajectory for entering raw data into k-space. Zigzag-type trajectories can be achieved that have flanks without curvature, or without significant curvature. Cartesian methods for image reconstruction of parallel MR imaging are applied to echo planar MR imaging with such zigzag-type trajectories.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention concerns a method for echo planar magnetic resonance imaging wherein raw data are acquired (entered into k-space) with a zigzag-type trajectory, as well as a magnetic resonance apparatus for implementing such a method. In particular, the invention concerns applying a certain series of phase encoding gradient fields, which enable the zigzag-type trajectory. The invention also concerns techniques for parallel imaging employing the zigzag-type trajectory.[0003]2. Description of the Prior Art[0004]Magnetic resonance (MR) tomography is an imaging modality that enables acquisition of two-dimensional or three-dimensional image data sets that allow structures in the interior of a patient to be shown in an image with a spatial resolution. MR data are acquired by operating an MR data acquisition unit magnetic to align magnetic moments of protons in a patient in a basic magnetic field or main magnetic field (...

AI Technical Summary

Benefits of technology

[0054]Because neighboring flanks of the same class proceed in parallel with respect to each other and preferably have no or only a small curvature, it can be possible to use simple known methods for parallel MR image reconstruction, e.g., with respect to Cartesian k-space trajectories. This is because trajectories in Cartesian k-space sampling ca

Problems solved by technology

Susceptibility artifacts can lead to image distortions that depend, inter alia, on the time between the various echoes of a gradient echo sequence (echo spacing).

Further, the T2* relaxation can limit the possible resolution.

Besides these physical limitations, it is also possible for further technical requirements of MR apparatuses and EPI imaging to be comparably demanding.

For example, typical EPI sequences impose high demands on the MR apparatus, because a comparably large number of gradient fields are rapidly switched.

Mechanical vibrations caused by this can lead to strong noise generation, which not only reduces patient comfort, but also requires a more sophisticated protection for the hearing of the patient (two-fold heari

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